This invention relates to providing a range indicator on a display representing a selected physical distance from an object, and more particularly on displays of traffic in the flight deck of aircraft, such as a cockpit display of traffic information (CDTI).
Traffic of interest is displayed to the pilot of an aircraft on a cockpit display of traffic information (CDTI). A CDTI display typically displays nearby target aircraft and information about the target aircraft, such as their altitude, heading, and identification. This information may be received from one or more sources, including Traffic Information Service (TIS) from ground air traffic control, and Automatic Dependent Surveillance-Broadcast (ADS-B) from transmitters on other aircraft, vehicles, or fixed structures. A CDTI may allow traffic to be displayed 360 degrees around a symbol of the pilot""s own aircraft, or may display an arcuate area in front of the pilot""s own aircraft, in which case the own aircraft symbol is placed toward the bottom edge of the screen.
A primary task for pilots is to be aware of nearby air traffic by maintaining a constant visual scan. If traffic is sighted, the pilot must first assess the threat posed by the intruder aircraft, then, if necessary, maneuver to avoid the other aircraft. This strategy is termed xe2x80x9csee-and-avoid.xe2x80x9d The effectiveness of see-and-avoid depends on the ability of a pilot to visually acquire the intruder aircraft early enough in the encounter to enable threat assessment and avoidance. A CDTI assists the pilot with see-and-avoid by providing a display for nearby traffic when the pilot""s aircraft is equipped to receive traffic information, and the nearby traffic is equipped to transmit their position information.
The ability to control the display of traffic is desirable to allow the pilot to de-clutter the display and focus on targets of interest. The ability to determine from the display the actions of nearby aircraft relative to the aircraft containing the display is also desirable for effective threat assessment and avoidance. Thus, there is a need for enhancements to CDTI units to provide graphic indications to help pilots track the actions and the status of nearby aircraft.
Prior systems have provided a xe2x80x9crange ringxe2x80x9d on the CDTI to mark the position half way to the periphery of the screen, where a compass rose is often displayed. Such a xe2x80x9chalf-scalexe2x80x9d range ring may be a complete circle if the display is a full 360 degrees, or an arc if the display shows only the forward arcuate area. Multiple range rings have been provided, with the range rings being placed, for example, at one-third or one-quarter intervals. The pilot conventionally can alter the scale of the area shown on the screen. When this occurs the distance represented by the compass rose varies, and the distance from the pilot""s own aircraft represented by the range ring changes in proportion. In other words, the spacing on the display screen from the own aircraft symbol to the range ring remains constant, but the physical display screen distance between the own aircraft and a target initially shown astride the range ring changes when the range scale changes.
If a pilot is monitoring the position of a target aircraft relative to the range ring, a change to the range scale changes the meaning of the target""s position relative to the range ring. For example, if the range scale is set at 20 nautical miles at the position of a peripheral compass arc 20, as shown in FIG. 2A, the range ring 30h represents 10 nautical miles, and a target 60 positioned 8 nautical miles from the own aircraft is shown inside the range ring. If the pilot changes the range scale to a maximum of 10 nautical miles, as shown in FIG. 2B, the range ring represents 5 nautical miles, and the same target immediately appears far outside the range ring. The pilot may need to exercise some mental effort to adjust his or her perception to continue monitoring the target aircraft.
Thus, there is a need for a range indicator system that makes it easier to monitor the position of a target relative to the range indicator after a change in the overall range scale of a display.
The present invention is an improvement in displaying traffic information on a CDTI. The invention seeks to provide a range indicator system that makes it easier to monitor the position of a target relative to a range indicator after a change in the overall range scale of a display.
This object is accomplished in the present invention by moving the position of a range indicator on a display to maintain the indicator at a set physical distance represented by the indicator as the range scale of the display changes. Generally described, the present invention provides a method and system for displaying information on an electronic display relative to an object of known location, by providing a range indicator on the display representing a selected physical distance from the object; and moving the range indicator in a fixed distance mode to maintain the selected distance represented by the indicator while changing the scale of physical distance represented on the display.
In a preferred embodiment, the invention may also provide for selection, in the alternative, of a more traditional set-scale distance mode in which the range indicator is held at an initial position on the display while changing the scale of physical distance represented on the display. In this case, the physical distance from the object represented by the indicator is altered. The method and system of the invention may allow a user to choose either the fixed distance mode or the set-scale distance mode, and prompt a user choosing the fixed distance mode to enter a selected physical distance to be represented by the indicator. For example, the prompting may be provided by displaying a data entry area adjacent to the range indicator. Preferably, the fixed and set-scale modes of the range ring are visually distinguishable by way of a varied visual characteristic associated with the range indicator. For example, the manner or format of showing a numeral representing the distance of the range indicator from the object may be varied.
In a preferred embodiment, the electronic display is a cockpit display of traffic information, the object is an aircraft containing the display, and the range indicator is a range ring. The data entry areas then may be one or more text boxes adjacent to or intersecting the range ring. As an additional optional feature, an alert may be provided when a target is at or within the distance from the object represented by the range ring.
According to a more specific embodiment, the invention may provide an electronic cockpit display of traffic information in a pilot""s own aircraft, comprising: a traffic display out to a distance from the own aircraft at a periphery of the display set by an adjustable scale; and a range indicator display representing a selected physical distance from the own aircraft, the range indicator moving in a fixed distance mode to maintain the selected distance from the own aircraft represented by the indicator as the adjustable scale changes. The range indicator display optionally may be selectively operable in an alternative set-scale distance mode, in which the range indicator remains at an initial position on the display as the adjustable scale changes, and in which the physical distance from the own aircraft represented by the indicator varies with the scale adjustment.
Thus it will be seen that a pilot using a display embodying the invention can choose to maintain the relative position of a target and a range ring when varying the range scale of the display, and in doing so can more easily track the position of the target.
Other features and advantages of the present invention will become apparent to one skilled in the art upon examination of the following drawings and detailed description. It is intended that all such features and advantages be included herein within the scope of the present invention as defined by the appended claims.